# Open-source automatic coil winder built for flip-dot matrix displays

> **Key takeaway:** A maker built a 3D-printed, Teensy-controlled automatic coil winder to produce the hundreds of electromagnetic coils needed for a custom flip-dot matrix display.

**Published:** 2026-10-23T23:00:07+00:00 
**Source:** Hackaday Hardware 
**Category:** open-hardware 
**Canonical URL:** https://fosswire.org/news/open-source-automatic-coil-winder-built-for-flip-dot-matrix-.html 

## Summary
Hackaday contributor [Larry] designed and built an open hardware automatic coil winder to solve a practical problem in his flip-dot matrix display project. Each dot in the display requires two electromagnetic coils, making hand-winding impractical. The machine uses two stepper motors for winding and wire distribution, with a Teensy microcontroller providing control via an OLED display and rotary encoder interface. The mostly 3D-printed design with metal rods, bearings, and belt drives is documented as a reproducible maker project.

## How the winder works
- Two stepper motors: one winds wire onto the bobbin, one moves the guide carriage for even distribution
- Bobbin retainer holds the bobbin and serves as a tie point for the wire end
- Wire spool rotates on bearings; foam pieces provide adjustable tension
- Teensy microcontroller handles motion control with homing via end-stop switch
- OLED display and rotary encoder form the user interface
- Machine tracks layer count automatically during winding

## Why it matters
The project lowers the barrier for makers building electromagnetic actuators at scale, and joins a growing body of open hardware tooling for small-batch manufacturing of components that are otherwise tedious to produce by hand.